The answer to 'how to fix system upgrade' is that upgrading your HVAC system is a complex process that often requires professional help. While some minor upgrades can be done by homeowners, major system replacements or retrofits should be handled by a licensed and experienced HVAC technician.
Upgrading your HVAC system involves properly sizing the new equipment, ensuring it is compatible with your home's ductwork and electrical system, and following all local building codes and safety regulations. An expert HVAC technician will be able to assess your current system, recommend the best upgrade options, and handle the installation process safely and efficiently.